[Boost-bugs] [Boost C++ Libraries] #6059: uniform_real_distribution fails when _min = _max

Subject: [Boost-bugs] [Boost C++ Libraries] #6059: uniform_real_distribution fails when _min = _max
From: Boost C++ Libraries (noreply_at_[hidden])
Date: 2011-10-25 19:53:38

#6059: uniform_real_distribution fails when _min = _max
---------------------------------------+------------------------------------
 Reporter:  dario.izzo@…               |       Owner:  steven_watanabe
     Type:  Bugs                       |      Status:  new            
Milestone:  To Be Determined           |   Component:  random         
  Version:  Boost 1.47.0               |    Severity:  Problem        
 Keywords:                             |  
---------------------------------------+------------------------------------
 Connected to BUG report #6053.

 Even though all asserts require only that _min <= _max, the condition
 _min=_max seems to be not handled correctly. Consider the code


 {{{
  #include<boost/random/uniform_real_distribution.hpp>
  #include<boost/random/lagged_fibonacci.hpp>
  #include<iostream>

  int main() {
  boost::lagged_fibonacci607 rng(32);
  double r = boost::random::uniform_real_distribution<double>(90,91)(rng);
  std::cout << r << std::endl;
  r = boost::random::uniform_real_distribution<double>(50,50)(rng);
 std::cout << r << std::endl;
  return 0;
  }
 }}}

 the second std::cout will never execute as an infinite loop is encountered
 before. The problem is in boost/random/uniform_real_distribution.hpp and
 in particular at generate_uniform_real line:
 {{{
 if(result < max_value) return result;
 }}}

 If min_value == max_value the condition above is never met as result =
 min_value = max_value ALWAYS.

 A solution (the one I am currently using) could be

 {{{
 if ( (result < max_value) || (max_value==min_value) ) return result;
 }}}

-- 
Ticket URL: <https://svn.boost.org/trac/boost/ticket/6059>
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